<!DOCTYPE html>
<html lang="zh-CN">

<head>
  <meta charset="utf-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Bootstrap 101 Template</title>
  <link href="https://cdn.jsdelivr.net/npm/bootstrap@3.3.7/dist/css/bootstrap.min.css" rel="stylesheet">
</head>

<body>
  <div class="container">
    <h1>你好，世界！</h1>
    <hr>
    <div class="col-xs-3">
      <input type="text" class="form-control">
    </div>
    <button class="btn btn-primary">点击登录</button>
  </div>
</body>

</html>